Web/JavaScript/Reference/Operators/Unary plus

The unary plus operator (+) precedes its operand and evaluates to its operand but attempts to convert it into a number, if it isn't already.

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Syntax

Operator: +x

Description

Although unary negation (-) also can convert non-numbers, unary plus is the fastest and preferred way of converting something into a number, because it does not perform any other operations on the number. It can convert string representations of integers and floats, as well as the non-string values true, false, and null. Integers in both decimal and hexadecimal (0x-prefixed) formats are supported. Negative numbers are supported (though not for hex). Using the operator on BigInt values throws a TypeError. If it cannot parse a particular value, it will evaluate to NaN.

Examples

Usage with numbers

const x = 1;
const y = -1;

console.log(+x);
// 1
console.log(+y);
// -1

Usage with non-numbers

+true  // 1
+false // 0
+null  // 0
+function(val){ return val } // NaN
+1n    // throws TypeError: Cannot convert BigInt value to number

Specifications

Specification

ECMAScript (ECMA-262)The definition of 'Unary plus operator' in that specification.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
Unary plus (`+`)	Chrome Full support 1	Edge Full support 12	Firefox Full support 1	IE Full support 3	Opera Full support 4	Safari Full support 1	WebView Android Full support 1	Chrome Android Full support 18	Firefox Android Full support 4	Opera Android Full support 10.1	Safari iOS Full support 1	Samsung Internet Android Full support 1.0	nodejs Full support 0.1.100

Legend

Full support: Full support